Mechanical fittings for joining pipe elements together end-to-end comprise interconnectable housing portions that are positionable circumferentially surrounding the end portions of pipe elements. The term “pipe element” is used herein to describe any pipe-like item or component having a pipe-like form. Pipe elements include pipe stock, pipe fittings such as elbows, caps and tees as well as fluid control components such as valves, reducers, strainers, restrictors, pressure regulators and the like.
Toothed retainers may be used to form projections for fittings connecting plain end pipe elements. When the retainers are properly oriented in the housing portions engagement between the teeth and the pipe elements provides mechanical restraint to the joint and ensures that the pipe elements remain coupled even under high internal pressure and/or external forces. The housings also define annular channels that receive ring gaskets, typically elastomeric rings which engage the ends of each pipe element and cooperate with the housing portions and the pipe elements to provide a fluid tight seal. The housing portions have connection members, typically in the form of lugs which are arranged in facing relation. The lugs are adapted to receive fasteners, such as nuts and bolts, which are adjustably tightenable to draw the housing portions toward one another.
Some retainers use teeth that are angularly oriented with respect to a radius from the center of the pipe elements. The proper angular orientation allows the teeth to be “self-actuating”, i.e., the mechanical engagement between the teeth and the pipe elements increases with increasing force on the pipe elements trying to draw them out of the fitting. Hence, the force resisting withdrawal increases with the applied force that would otherwise cause withdrawal. However, if such retainers are oriented improperly, for example, if the retainer is reversed within the fitting, then it will not provide sufficient mechanical engagement against withdrawal and the pipe elements will not be securely held within the fitting. For fittings having retainers it may be difficult to determine if the retainers are properly oriented before the joint is pressurized. It would be advantageous if pipe fittings could be designed so that, during assembly of the joint, there is an indication that the retainer was not properly oriented during assembly of the joint.